1. Field of the Invention
The present invention relates to a novel greasy oil and fat composition for food processing machines. More particularly, the present invention relates to a novel greasy oil and fat composition for food processing machines which is safe for food sanitation, excellent in oxidation stability and lubricating property and favorably utilized as lubricating oil for machines utilized for food processing.
2. Description of the Prior Art
For processing of agricultural products, livestock products, marine products and other materials to prepare food stuffs, various processes, such as selection, classification, grinding, mixing, baking, heating, fermentation, boiling, drying freezing and the like, are generally applied to the material and various kinds of food processing machines are utilized in these processes.
Examples of the machines for processing of agricultural products are machines and tools for collecting leaves from tea plants, rice cleaning machines, flour mills, brewing apparatus for production of sake, soy sauce, miso and like others and machines for production of noodle, bread, cookies, fruit, juice, jam, pickles and like others. Examples of machines for processing of livestock products are machines for processing milk, machines for production of milk products, such as cheese and butter, machines for processing meat and like others. Examples of machines for processing of marine products are machines for processing of fish meat, machines for processing sea weeds and like others. Other examples of the food processing machines are apparatus for production of food additives, natural flavor and pharmaceutical products, such as a vacuum thin layer evaporator and a mixing apparatus.
As lubricant for the food processing machines, grease based on mineral oil is generally utilized. In the grease based on mineral oil, purified mineral oil is used as the base oil and inorganic compounds, such as metal soap of lithium, potassium and sodium, or organic compounds, such as urea derivatives, are dispersed in the base oil as a thickening agent to make the grease semisolid or solid form.
However, when grease based on mineral oil is utilized, it is unavoidable that the grease is scattered or mixed into the foods or the agricultural products through rotating parts of the machines during long operation of the machines and the scattering and mixing of the grease based on mineral oil is not desirable food sanitation.
To avoid problems on environment and human health, grease made only from those materials which are permitted as food and food additives were proposed as following: (1) an industrial lubricating oil of low environmental hazard made from glycerides of fatty acids, fatty acids, silicone resins and 2,6-di-t-butyl-4-methylphenol which are permitted as food or food additives by the food sanitation law (Laid Open Japanese Patent Publication Showa 51-84803); (2) a lubricating oil for food processing machines in which glycerides of saturated fatty acids of 5 to 21 carbon atoms are used as the base oil and fatty acids of 12 to 22 carbon atoms are compounded to the base oil (Laid Open Japanese Patent Publication Heisei 2-209995); and (3) a high viscosity oil and fat composition prepared by transesterification of oils and fats for food and natural wax (Laid Open Japanese Patent Publication Showa 57-67694).
However, the lubricants of (1) and (2) described above can not be utilized as grease because they are liquid at the ambient temperature even though they are safe for food sanitation. The high viscosity oil of (3) described above has a problem that oxidation stability is inferior because soy bean oil and rapeseed oil are used as the materials even though it is safe for food sanitation and very viscous liquid at the ambient temperature.